Cyclopentanophenanthrene derivatives and process for the production thereof



United States Patent CYCLOPENTANOPHENANTHRENE DERIVA- TIVES AND PROCESS FOR THE PRODUC-v TION THEREOF Carl Dje rass i, Birmingham, Mich, and Franz Sondheimcr and George Rosenkranz, Mexico City, Mexico, assignors to Syntex S. A., Mexico City, Mexico,a corporation of .Mexico I No Drawing. Application November 27, 1953,

Serial No. 394,904

\ priority, application Mexico November 27, 1952 V 5 Claims. (Cl; 260-23955) formation l Thioketal tisone (I. A. C. S. 74, 483 (1952)).

well as the preparation of certain novel intermediates for the production of this compound.

'22a-spirostan-3a-o1-1l-one is an; extremely important intermediate for the preparation of cortical hormones such as cortisone from compounds of the sapogenin series, since in addition tohaving the ll-keto group characterizing cortisone, it also possesses the normal configuration at C-5. Degradation of this compound then, as pointed out hereinafter produces the normal pregnan-3a-ol-1L20- dione, a known intermediate for the production of cor- In accordance with the present invention, it has been discovered that A -22a-spirostadien-3-one, which may be prepared in accordance with the United States application of Rosenkranz and Djerassi, Serial No. 219,532, filed April 5, 1951, now abandoned, may be readily converted to various intermediates and finally to 22a-spirostan-Ba-ol-ll-one and/ or esters thereof.

A portion of the process of the present invention may 20 be exemplified by the following equation:

Reduction followed by acetylation lit U *1 I Oxidation Reduction Zinc, acetic acid o Catalytic V S -CH2 i A 0- -desulfurization H S CH2 H r v I Oxidative E v degradation I ({I'Hs Hydrogenation i AcO- Patented Apr. 30, 1957 able" solvent, such as anhydrous tetrahydrofuran-and' isthen be treated with an agent capable of selectively removing the 7-keto group. Thus, the dione may be subjected to Wolff-Kischner reduction especially as set forth by Huang Minlon in United States Patent No. 2,471,697, or as indicated in the above equation, the 7-thioketal may be produced selectively by reaction of the dione with ethanedithiol and the resultant thioketal catalytically desulfurized. In any event the resultant compound is the corthenjadded to asolution of lithiumaluminum' hydride in; V

a similar solvent. The mixture is refluxed for a'shortperiod' of time,,- as for exampleoner-hour, and thenrooled in ice. Thereafter the excess reagent is destroyedg by.the-ad-" dition of water' and :the product suitably purified to yield the corresponding M 9-22a=spirostadien-3a olo Although lithium aluminum hydride is-the preferred reduc ing agent; for this reaction it may be understood that other well-known reducingageuts capable of reducing steroid ketones to the corresponding steriodalcohols may be utilized for this step. The'corresponding acetate or other ester of the A -22a-spirostadien-3a-ol was then responding acetate of 22a-spirostan-3a-ol-ll-one, or if the free compound has been utilized for the foregoing steps as previously set forth the resultant compound is the free alcohol.

Either the free compound of the acetate of 22a-spirostan-3a-ol-11-one' may then besub'jected to oxidative degradation as for example'by heating this compound in a pressure bomb with acetic anhydride, followed by oxidation of the product with chromic acid. Suitable purification of the resultant product then gave, in either case, the acetate of A -pregnen-3u-ol-11,20-dione. As indicated, catalytic hydrogenation of the A compound then produces the known acetate of ll-keto pregnanolone, i. c. pregnan-3a-ol-1 1,20-dione.

The following equation illustrates a further treatment of the product of the first oxidation step, namely the aceprepared' by suitable treatment with the conventional a'cyltate of A -22a-spirosten-3a-ol-7-one:

The 3-ester of A -22a-spirostadiene-3a-ol prepared WH I in accordance with the previously set forth step was then dissolved in a suitable solvent such as benzene and oxidized with an oxidizing agent such as sodium dichromate. Two compounds were prepared as a result of this-oxidation, i. e. the ester or acetate of A -22a-spirosten+3u-ol- 7-one, which could be crystallized from a suitable solvent and the acetate of A -22a-spirosten-3a-ol-7,ll-dione which could be separated from the mother liquor. The esters of A -22a-spirosten 3a-ol-7,1l-dione could be saponified to prepare the corresponding free compounds by utilizing a conventional saponifying agent and either the esters, as for example the acetate, or the free compounds could be used for the subsequent steps of the above-out"- lined process.

The oxidation product of the previously outlined step, as for example the acetate of A -22a-spirosten-3a-ol7,11- dione was dissolved in a suitable solvent such as acetic acid and reduced as for example with zinc dust to prepare the corresponding saturated compound, namely the acetate of 22a-spirostan-3a-ol-7,ll-dione. This dione may l Sapontflcatlon In the" above equation Ac represents the acetyl group formation as previously set forth.

In practicing the processes above-outlined, the acetate or other ester of A -22a-spirosten-3a-ol-7-one is treated with potassium hydroxide to produce A -22aspirosten-3a-ol-7-one. This compound is then treated with isopropenyl acetate to prepare the corresponding A -22a-spirostadiene-3a,7-diol as set forth in the above equation. This last compound may also be utilized as an intermediate since the diacetate of A 22a-spirostadiene-3a,7-diol upon treatment with an aromatic peracid, such as pcrbenzoic acid, gives A -22a-spir0- sten-3a,llu-diol-7-one 3-monoacetate. The monoacetate thus produced upon oxidation with chromic acid or sodium dichromate then gives the A -22a-spirosten-3a-ol- 7,11-dione 3-monoacetate, which is identical with the same compound previously referred to.

The following specific examples serve to illustrate but are not intended to limit the present invention:

Example I Under anhydrous conditions, a solution of 2 g. of 41 -22a-isospir0stadiene-3-one in 50 cc. of anhydrous tetrahydrofurari was added to a solution of 1 g. of lithium aluminum hydride in 20 cc. of tetrahydrofuran and the D Oxidation AcO- 0 mixture was refluxed for one hour and cooled in ice. The excess reagent was destroyed by the careful addition of water, the mixture was acidified with sulfuric acid and the tetrahydrofuran was distilled. The precipitate formed was collected and washed with'water until neutral. Recrystallization from chloroform-methanol yielded 1.84 g. of A -22a-spirostadiene-3u-ol having a melting point of'209-2l2 C., [a], +20 (chloroform).

The acetate of the above compound was prepared by conventional acetylation procedure (acetic anhydridepyridine) and had a melting "point of l50153 C., [111 +44 (chloroform).

The benzoate .was also conventionally prepared. It had a melting point of 198200 C., [@1 +57 (chloroform).

Example 11 A solution of 17.5 g. of sodium 'dichromate dihydrate in 150 cc. of acetic acid was added dropwise to a stirred solution of g. of the acetate of A -22a-spirostadiene-3a-ol in 150 cc. of benzene maintaining the temperature at C. After standing overnight at room temperature, the mixture was poured into water and extracted with ether. The ether solution was washed with water, with sodium carbonate solution and water until neutral, dried and evaporated to dryness. The residual oil was chromatographed in a column with 500 g. of washed alumina. The fractions having an ultraviolet absorption maximum at 272 m were combined. Crystallization from chloroform-methanol yielded first the acetate of A -22a-spirosten-3a-ol-7-one having a melting point of 220222 C., [ocJ -60 (chloroform).

From the mother liquors of this little soluble substance, the acetate of A -22a-spirosten-3a-ol-7.ll-dione was obtained, having a melting point of l46-l48 C., [al --l7 (chloroform), ultraviolet absorption maximum at 272 mp, log E 4.04. The infrared spectrum of this substance exhibits the characteristic bands at 1736 and 1674 cmr showing the presence of an acetyl and an unsaturated keto group. Conventional saponification produced the corresponding free A -22a-spirosten-3a-ol- 7,11-dione.

Example 111 A solution of 5 g. of the acetate of A -22a-spirosten'3aol-7,ll-dione in 500 cc. of acetic acid was shaken at a temperature of 91 C. for 3 hours with 30 g. of zinc dust. The zinc was removed by filtration and the solution was poured into water. The precipitate was collected and washed with water until neutral. After one crystallization from chloroform-pentane, 2.5 g. was obtained of the acetate of 22a-spirostan-3a-ol-7,1l-dione having a melt ing point of l84186 C. The infrared spectrum showed characteristic bands at 1736 and 1718 cmr indicating the presence of an acetyl and a saturated 7,11-diketone group. Conventional saponification produced the corresponding free 22a-spirostan-3a-ol-7,1l-dione.

Example IV A solution of 7.88 g. of the acetate of 22a-spirostan- 3a-ol-7,11-dione in 100 cc. of acetic acid was mixed with 7.9 cc. of ethanedithiol and 4 cc. of a saturated solution of hydrogen bromide in acetic acid. The mixture was acetyl group, the infrared spectrum showed a band at cm.- indicating the presence of the ll-keto group.

evaporated to dryness.

' Example V 3.8 g. of the product of Example IV was dissolved in 3 l. of ethanol previously distilled over Raney nickel and the solution was, refluxed for six'hours inthe. presence of 50 g of Rariey nickel. The nickel was removed by filtration and the filtrate was evaporatedfto dryness at low temperature underreduced pressure. The residue was dissolved'in chloroform, washed to neutral and again Recrystallization from ether afforded the acetate of 22a-spirostan-3a-ol-1l-one with a melting point of 1 79f-18,l C. This compound had essentially the same-infrared bands as the compound obtained in accordance with Example III (1736 and 1714 cmr [aJ "+10 (chloroform). Conventional saponification gave the free 22a-spir0stan-3u-ol-1l-one.

Example V1 at '175180 Cr After cooling, the mixture was poured into water, extracted with ether, washed with water, dried over sodium sulfate and evaporated to dryness. The residual oil was dissolved in 40 cc. Of acetic acid and 35 cc. of ethylene dichloride, cooled to 15 C. and treated dropwise under stirring with a solution of 1.1 g. of chromic acid in 2 cc. of water and 20 cc. of acetic acid. After two hours standing at room temperature, the mixture was diluted with water, extracted with chloroform, washed with water, dried and evaporated to dryness. The residue was chromatographed in a column with unwashed alumina, thus giving 250 mg. of the acetate of A -pregnen-3a-ol-l1,20-dione with a melting point of 205 -206 C. which could be conventionally saponified to the free compound. Catalytic hydrogenation of this compound (preferably the acetate) with 10% palladium on charcoal catalyst and ethyl acetate as solvent yielded the acetate of ll-keto-pregnanolone (pregnan-3a-ol- 11,20-dione) having a melting point of 131134 C., [UJD +129 (chloroform), which showed no depression in the melting point in mixture with an authentic sample.

Example VII 400 mg. of the product of Example VII was dissolved in 16 cc. of benzene and 2 cc. of isopropenyl acetate and the mixture was refluxed for six hours maintaining a slow distillation through a fractionating column. At the end of three hours, one additional cc. of isopropenyl acetate was added, and two cc. more at the endof the fourth hour. The solution was evaporated to dryness and the residue was dissolved in ether, washed with sodium bicarbonate and water, dried over sodium sulfate and evaporated to dryness. Crystallization from acetone-pentane yielded the diacetate of A -22a-spirostadiene-30:,7- diol having a melting point of 172l74 C. (Kofler 178-l80 C.), [a] +76 (chloroform), ultraviolet absorption maximum at 242 mp. (log E 4.35).

We claim:

1. A process for the preparation of a compound selected from the group consisting of 22a-spirostan-3uol-ll-one lower fatty acid esters and the benzoic acid ester thereof which comprises treating the corresponding ester of A -22a-spirostadicne-3a-ol with sodium dichromate to produce the corresponding ester of A -22a? splrosten-3a-ol-7Jl-dionc,:imaling the A -ester with a reduci gg ggcnt to produce the corresponding .22a-spirostgn-Iliwol-flJL-dione ester, and thereafter selectively removingwthe 'Z-keto gronpjfrom the 7,11-dione ester by forming .the 7-,thioketal thereof followed by Raneytnickel desulfurizat'ion of, .the othivbketal.

.2.A,;process for the "Preparation of a compound.

selected. vfr,om,. ,the group consisting .of 22a'spirostan-3 a, okIL-one lowerQfatty a'cid esters and the benzoic acid esterkthereof whichcqmprises "selectively removing the C-.7; kegqgrqup of -21 compoundQselected from a grogp consisting of ,22arspirostzm 3 u-ol?7; 1'l dione ,and esters by forming the 7-.thiol etqil thereof followed by "Raney nivC kcl, ,desulfurization of the ,thioketal thereof.

,3..A process "for jthemreparation ofjthe acetate of 22a-spirostan-3a-ol-l'l one, which comprises selectively forming a 7-thioketal ofthe'acetate of 22a-spirostan-3ao1-7,l l-edione and treating the, thioketal with ,Raney. nickel catalyst.

-4. Anew. compoundselected from-the group consisting 20 :ReterencemGnedmthe file of mispatent UNITEDSTATES [PATENTS Re. 23,008

QTHER REFERENCES .vHauptman: INA. Chem. Soc., pp. 4562566LMarch 15 1947, vol. 69. 

1. A PROCESS FOR THE PREPARATION OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 22A-SPIROSTAN-3AOL-11-ONE LOWER FATTY ACID ESTERS AND THE BENZOIC ACID ESTER THEREOF WHICH COMPRISES TREATING THE CORRESPONDING ESTER OF $7,9(11)-22A-SPIROSTASIENE-3A-OL WITH SODIUM DICHROMATE TO PRODUCE THE CORRESPONDING ESTER OF $8-22ASPIROSTEN-3A-OL-7,11-DIONE, TREATING THE $8-ESTER WITH A REDUCING AGENT TO PRODUCE THE CORRESPONDING 22A-SPIROSTAN-3A-OL-7,11-DONE ESTER, AND THEREAFTER SELECTIVELY REMOVING THE 7-KETO GROUP FROM THE 7.11-DIONE ESTER BY FORMING THE 7-THIOKETAL THEREOF FOLLOWED BY RANEY NICKEL DESULFURIZATION OF THE THIOKETAL. 